Vacuum flask



FIG. 1 is a front elevation view of the vacuum flask showing my new design;

FIG. 2 is a side elevation view thereof;

FIG. 3 is a rear elevation view thereof;

FIG. 4 is a top plan view thereof;

FIG. 5 is an exploded side elevation view thereof;

FIG. 6 is a top plan view thereof without the cup; and,

FIG. 7 is a bottom plan view of the cup. 

The ornamental design for a vacuum flask, as shown and described. 